Scanning laser acoustic microscopy ( SLAM) was used to visualize creep damage distribution in the gas-pressure-sintered silicon nitride after creep at 1300degreesC in 4-point bending. SLAM revealed asymmetrical distribution of creep damage beneath the tensile surface and in a narrow zone that spread continuously across the neutral axis toward the compression surface. Scanning and transmission electron microscopy confirmed the presence of cavities in tensile zone of bending bar. The combination of the homogeneous cavity development in the zone of tensile stresses and formation of the damage zone ahead of main crack was proposed to explain such cavity distribution. Current SLAM observation is a direct evidence of cavitation asymmetry in vitreous bonded ceramics. Such distribution supports the model of simultaneous presence of cavitation and non-cavitation creep mechanisms in silicon nitride and similar ceramics. (C) 2003 Kluwer Academic Publishers.